1. Field of the Invention
This disclosure generally relates to microchip systems formed on chips or wafers, and to the manufacturing and/or operation of the same.
2. Description of the Related Art
Microchip systems are becoming increasingly complex as micro-fabrication techniques permit the formation of integrated circuits with ever decreasing dimensions, thereby allowing an ever increasing number of circuit components to be formed on a wafer or chip. The increase in complexity and the increase in the number of components also increases that probability that a fault will occur during the fabrication process, resulting in one or more faulty components, and consequently rendering the resulting microchip system unusable. This is particularly troublesome as the number of manufacturing operations increases, since significant costs will in incurred in producing an unusable product. Those costs may include lost time, money and materials used in creating the faulty microchip system, treatment and/or disposal of the resulting waste, and the reduced throughput of the expensive equipment used in the micro-fabrication process.
In a similar vein, progress in nano-technology including manufacture of MEMS devices is making sophisticated lab-on-chip systems, also known as total analysis systems (μTAS), commercially viable. Such lab-on-chip systems are one specific subset of microchip systems. Lab-on-chip technology uses integrated circuit like micro-fabrication techniques to translate experimental and analytical protocols into chip architectures, typically formed as fluid reservoirs and interconnected pathways
The lab-on-chip systems typically employ one or more MEMS devices, which may take a variety of forms. For example, MEMS devices may take the form of various microfluidic devices capable of performing operations on small bodies of fluids and/or on particles suspended in a fluid, for example, a colloidal suspension. Microfluidic devices commonly employ fluids such as whole blood samples, bacterial cell suspensions, protein or antibody solutions, and various buffers, and reagents.
Microfluidic devices may include one or more channels typically with a dimension less than one millimeter, or may take the form of a channeless field or array. Microfluidic devices may employ pumps, valves, gears, electrodes and other structures, which typically have analogs on the macroscopic world, to move fluids and/or suspended particles using, for example, pressure or electrokinetic forces. The controlled movement may be employed to combine materials, divide materials, concentrate materials, direct materials to reagents, etcetera.
Microfluidic devices may be used to obtain a variety of measurements including molecular diffusion coefficients, fluid viscosity, pH, chemical binding coefficients, and enzyme reaction kinetics. Other application for microfluidic devices include capillary electrophoreses, isoelectric focusing, electrowetting, immunoassays, flow cytometry, sample injection of proteins for analysis via mass spectrometry, PCR amplification, DNA analysis, cell manipulation, cell separation, cell patterning and/or chemical gradient formation. Many of these applications have utility for clinical diagnostics.
Lab-on-chip systems may have several advantages over conventional laboratory systems. For example, such systems typically have a smaller physical footprint than standard laboratory setups, and have low power consumption. Micro-fabrication techniques permit simplified manufacturing and superior reproducibility, reducing costs. Lab-on-chip systems also provide the ability to work with very small volumes of samples, agents, reagents or other materials. This lowers the cost of materials, permits smaller samples to be taken from test subjects, such as patients, and also reduces disposal costs. Lab-on-chip systems may enhance automation leading to lower costs, higher throughput and more consistent results.
There is still significant room for improvement in the structure of lab-on-chip systems, and in the manufacture and operation of such device. Such improvements may be directed at reducing the cost of such devices, and making the devices more reliable and easier to manufacture and/or operate.